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Journal of Microwave Power
and Electromagnetic Energy (JMPEE) |
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TITLE |
Microwave Enhanced Diffusion
in Polymeric Materials [PDF] |
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AUTHORS |
C. Gibson,
1988 23 1 17-28 |
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Abstract A process is described
using microwave radiation (2.45 GHz) which, for temperature equivalence, greatly
accelerates the diffusion of ethylene oxide (EO) in polymeric materials
compared to that using conventional heating. The mechanism of action was
investigated in detail by examining the desorption
of EO from polyvinylchloride (PVC). The diffusion coefficient was found to be
dependent upon diffusant concentration. Values of
activation energy for diffusion were obtained from Arrhenius plots of the
logarithm of diffusion coefficient versus inverse temperature for both
conventional and microwave-enhanced diffusion, and there was a significant
reduction in activation energy for the latter. There is agreement, to within
the range of experimental error, between this value and an energy value equal
to the activation energy for conventional diffusion less the translational
kinetic energy of the diffusant molecules.
Therefore, it seems likely that the enhancement of the rate of diffusion of
EO in PVC using microwaves is brought about by the active disruption of the
EOJPVC hydrogen bonding resulting in a significant reduction in the
proportion of immobilized diffusant molecules at
any instant. This suggests that this process could be generally applicable
for enhancing diffusion for polar/polarizable
materials when a proportion of the diffusant
molecules are immobilized in the host material. |
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